1. Field of the Invention
The present invention relates to the microbiological industry, and specifically to a method for producing a non-aromatic L-amino acid using a bacterium of the Enterobacteriaceae family which has been modified to attenuate expression of the csrA gene.
2. Brief Description of the Related Art
The CsrA protein encoded by a pleiotropic gene csrA from Escherichia coli is a regulator of carbohydrate metabolism which affects glycogen biosynthesis, gluconeogenesis, cell size and surface properties (Romeo, T et al, J. Bacteriol., 175(15): 4744-4755 (1993)), glycogen degradation (Yang, H. et al, J. Bacteriol., 178(4):1012-7 (1996)), gluconeogenesis and glycolysis (Sabnis, N. A. et al, J. Biol. Chem., 270, 49, 29096-29104 (1995)). The CsrA protein also plays a regulatory role in biofilm dynamics (Jackson, D. W., J. Bacteriol., 184(1): 290-301 (2002)).
A microorganism having increased synthesis of aromatic compounds, useful particularly for producing phenylalanine, having decreased carbon storage regulator (CsrA) protein activity, and having increased content of erythrose-4-phosphate has been disclosed (WO0073484A1).
A process for the preparation of non-aromatic L-amino acids, in particular L-threonine, by fermentation of microorganisms of the Enterobacteriaceae family in which the csrA gene or nucleotide sequences which code for it are enhanced, in particular over-expressed, has also been disclosed (WO03046184A1).
But currently, there have been no reports of inactivating the csrA gene for the purpose of producing non-aromatic L-amino acids.